The development and widespread use of large trucks known as tractor trailers or semis has enabled the relatively efficient and economical movement of large amounts of cargo across long distances over our highways. A tractor trailer generally consists of a tractor which provides the locomotive force necessary to haul a detachable multiple-axle trailer which supports the cargo to be transported. The multiple-axle trailer component typically consists of a trailer chassis or underframe with a cargo-carrying bed mounted thereon, and an appropriate number of axles and wheels mounted to the chassis to support and distribute the weight of the cargo upon the road. The tractor and trailer are detachably connectable through conventional pivotable couplings, which are typically centered above the rear axle of the tractor, and which facilitate the turning of such multi-axle trucking rigs. A single axle or double axle may be provided in the rear of the tractor. At the rear of trailer, a single axle may be provided. But often times, especially for larger trailers or trailers carrying larger weight, there may a double axle provided at the rear of trailer. In a typical standard 18-wheeler tractor-trailer combination, the double axles of the rear of the tractor serve as the front axles of the trailer. As cargo weight increases, two or more sets of axles and wheel assemblies are often provided on the trailer.
The conventional covered trailer body is a flat bed with generally rectangular tall elongated enclosure having rigid walls and ceiling permanently mounted to the bed. One or more doors are typically provided on the rear or side panels or walls of the trailer enclosure for ingress into and egress from the trailer's interior. The enclosure also serves to protect the cargo from damage caused by various environmental sources and from theft and vandalism. One disadvantage of these conventional fully enclosed trailers is that they can only be used to transport certain types of cargo, namely cargo which can be easily loaded and unloaded through the rear or side doors. Boxes, crates, household appliances, and furniture that can be moved by hand or with a hand truck, and pallets of products or materials that can be readily moved by a small forklift truck are generally well-suited to transport with these conventional enclosed trailers. However, the loading and unloading of cargo in and out these trailers necessarily proceeds on first-in last-out basis. This is particularly true where the cargo is bulky, or is sufficiently heavy so that a forklift truck is required to pick up and move the various bundles or pallets of cargo. Further difficulties arise when extremely large, heavy, or irregularly shaped items need to be loaded and unloaded from these conventional trailers. For example, cargo such as large steel coils, large cable spools, long steel beams and bundles of long rods, bars or pipe are not generally well-suited to transport with a conventional enclosed trailer. These items are usually either so heavy (e.g., in excess of 1,000 pounds to a few tons) or so difficult to handle (e.g., steel beams or metal rod or pipe bundles may be 10 to 20 feet long and weigh a 1,000 pounds or more) that a power crane with a motorized winch and steel cable or heavy chain is typically needed to load and unload them. A conventional trailer does not provide a sufficient amount of unfettered access to the cargo within the trailer, especially from the top and side directions, to allow the use of any kind of overhead crane. Thus, it is very difficult to safely load or unload these types of cargo into a conventional enclosed trailer.
Another disadvantage of conventional enclosed trailers is that, when fully loaded, it is difficult to gain access to or inspect the cargo in front, especially if the only ingress to the trailer is located in the rear portion of the trailer, or the trailer is tightly packed, such as being loaded from floor to ceiling. In such cases, most if not all of the later-loaded cargo must be removed from the trailer in order to gain access to the cargo located in the forward portion of the trailer. This can be a problem if any kind of inspector wants to spot-check the contents of the trailer.
Still another disadvantage of conventional trailers is that the limited access to the interior areas may make it more difficult to safely secure certain types of cargo within the trailer against unwanted movement during transportation. The geometric shape, dimensions or weight distribution of certain kinds of cargo may render the cargo inherently unstable during any type of severe movement by the trailer, unless the cargo is carefully secured. The covered side walls and tops of most enclosed trailers severely limit the manner and means by which cargo may be secured.
Using flat-bed truck trailers is a common way to overcome the above-noted disadvantages of conventional enclosed trailers. Typically, flat-bed trailers are used to transport cargo which is not well-suited for conventional enclosed trailers. Flat-bed trailers normally do not have any kind of side walls or roof panels, and thus they permit unfettered access to the cargo from the top, side and even front and rear directions. Flatbed trailers may be modified to include cargo wells that are built into, or cargo-holding fixtures that are mounted on, the bed of the truck. Such wells or fixtures are often used with trailers that are to carry very heavy cargo, such as sheet steel coils or steel bar stock weighing a few tons. Their use ensures such modified flat-bed trailers will have to be loaded and unloaded from the top or the sides, since a forklift truck can be driven on such an irregularly shaped trailer bed. Such loading and unloading requirements in turn means that it is not possible to have a conventional permanently installed rectangular trailer enclosure mounted to the bed of a trailer that is used for such hauling purposes. Some flatbed trailers are modified by providing short side walls, having a height of a few inches to about two feet. Using these short walls means that loading of heavy objects must be handled from overhead, using a crane or other kind of hoist.
One significant disadvantage of flat-bed trailers is that they expose their cargo to the elements, potentially leading to damage to the cargo. Tarps or other protective coverings are often used, but even these allow some exposure to occur. Holes or tears in such protective coverings allow water, salt, and other unwanted substances to come into reach of the cargo. The tarps themselves may become dirty or covered with road dust, grit, grime and/or road salt. This undesirable exposure can either occur during actual transit (e.g., rain storms, water splashed upwardly by another passing vehicle, wind-blown rain or road mist or dirt or other debris) or during storage in parking lots or the like (e.g., rain or the falling dew in the evening tends to collect and concentrate atmospheric pollutants such as sulphur emissions, hence the term "acid rain"). Even dirty water dripping off of bridges, leaking overhead pipes and roofs, and chemical sprays or salty mists such as may be found at a truck wash, or near some factories or construction sites, or along the coastal highways near oceans, may also harm uncovered cargo.
The ability to protect cargo from such undesirable environmental exposure during transit and storage is becoming increasing important to the trucking industry. Damaged cargo leads to increased customer dissatisfaction and costs, increased insurance premiums, and interruptions and delays in manufacturing and delivery schedules. Customers are increasingly demanding that trucking concerns deliver cargo in an undamaged state.
Many types of cargo are susceptible to damage due to exposure to the elements or environmental factors or contaminants. These include water, ice, hail, extreme temperatures, solar radiation (particularly ultraviolet rays), chemicals (e.g., salt, oil, exhaust vapors from power plants or vehicles which can result in acid rain, gasoline byproducts, hazardous materials), and abrasive road debris (e.g., small rocks, sand, dust, asphalt byproducts, and loose road construction materials). All can have significant deleterious effects on different types of cargo.
Unfinished metal products and materials, such as sheet metal blanks, metal rods, pipes and even steel coils, are types of cargo that are especially susceptible to damage from these kinds of environmental sources. Typically, such products or materials are being shipped from a component plant, a stamping plant, bar or pipe mill, steel mill or foundry to another location where they will be further processed and/or assembled into a larger product such as a motor vehicle. Alternatively, they may be treated or coated with various substances, and then made into a component. For example, unfinished sheet metal blanks may be turned into car hoods or car fender panels or floor panels. During the finishing process, they may be painted or coated one or more times to enhance their ability to resist corrosion and other types of physical and chemical damage.
Exposure of unfinished metal goods or materials to environmental sources, especially salt, salt-laden water or road dust or grit, prior to being treated or coated, tends to compromise the future adherence of paint or other coatings to their unfinished surfaces. Further, these contaminants can eliminate or reduce the protective benefits of later surface treatments on such parts or materials, thus possibly leading to accelerated rates of rust or other surface damage on the finished products. Cleaning contaminated unfinished metal goods by hand, or by washing them with water or in expensive chemical baths laden with hazardous substances, may be required in order to restore their surfaces to an acceptable clean state for later coatings or painting. Such cleaning steps increase production costs and may create further pollution concerns, including waste water disposal issues.
The automotive industry is particularly interested in protecting bulky cargo from environmental damage during transit. Types of unfinished cargo which are at risk of being damaged by environmental factors and/or vandalism while in transit include blank steel and/or aluminum sheets cut to size, blank sheets already partially formed, racks of glass windshields, substantially completed automotive body panels, which are awaiting coating and/or painting and/or other further processing prior to final assembly.
For example, consider automotive blanks which are comprised of steel sheets which have already been stamped or shaped by power presses and are now to be shipped to another location for welding to other parts, painting, and/or other operations, including ultimately assembly into an automotive vehicle. Generally, these pre-formed steel blanks are stamped out by the hundreds or thousands. The steel sheets are typically stacked one on top of another in a nesting manner in order to make economical use of the available space both in the factory and during transport by tractor-trailer. Stacked steel sheets are generally placed upon steel pallets for shipment and often are secured in place by a plurality of registration pins or posts which extend through a plurality of aligned locating holes provided in the steel sheets, and carefully placed auxiliary strapping or banding as necessary. Such pallets help ensure the blanks are substantially immobilized relative to one another during shipment on flat-bed trucks from one location to another.
A problem arises during transportation when salt and/or grit (such as dirt, sand or dust), comes into contact with the exposed surfaces of the stacked steel sheets or blanks. Typically the top sheet, and side surfaces or edges of the individual intermediate sheets or blanks within the stack, will become contaminated. If they are not properly cleaned after transit, then the salt or grit will come into contact with the forming surfaces of the dies in the power presses or handling surfaces of the grippers in the automatic material handling equipment. This in turn leads to marks or blemishes on the finished parts when none should be present. Contaminants near the edges of the stamped steel blanks may interfere with the formation of quality welds.
In an effort to overcome these kinds of cargo contamination problems associated with flat-bed trailers, the trucking industry has attempted to cover the parts during shipment with canvas or other flexible tarps, such as plastic-covered fabric sheets. Tarps are often mounted on pay-out rollers to facilitate putting the tarps over the cargo and taking them off the cargo. Although useful, tarps are still labor intensive, in that they must be securely tied down to resist the road wind, and must be replaced periodically due to wear and tear, such as wind-shredding.
One effort to solve these problems has involved providing a trailer with tall rigid side walls and an open top that is covered by removable canvas. This arrangement has the drawback of restricting access to the cargo from the sides of the trailer, which makes it much more difficult to load and secure the cargo during loading, and to unsecure and remove the cargo during unloading.
Another effort to solve these problems has involved the use of a pleated accordion-style fabric-based enclosure to cover a flat-bed truck. Front and rear upstanding rigid metal bulkheads at the front and rear of the trailer bed provide support for anchoring the front and rear ends of the fabric enclosure. These flexible, pleated coverings are supported by transverse metal reinforcing hoops at regular intervals. (Thus they bear a certain resemblance to the covered enclosure used on the century-old horse-drawn Conestoga wagons.) In one conventional design, the hoops are supported by trolleys which ride on rails positioned along the outer side edges of a flat-bed trailer. This covering can be pulled forward, so that it collapses in pleated accordion fashion, thus providing access to most of the cargo space on the flat bed trailer to permit easy loading and unloading of cargo onto and off of the trailer. When in transit, the fabric covering is stretched taut between the front and rear bulkheads. However, these fabric-reinforced cover/enclosures on flat-bed trailers are susceptible to tearing, since they repeatedly billow in the wind as the trailer travels at highway speeds. They puncture readily, and tend to be drafty. They allow airborne contaminants (albeit in reduced amounts) to come into contact with the cargo within, and the billowing of the fabric sides may even pump ambient air and road dust into and out of the moving trailer.
Neither the tarps nor the Conestoga-wagon-style coverings provides much protection against swings in the temperature of the cargo due to ambient temperatures, Nor do they provide much security. Keeping the cargo from getting too cold or too hot is often desirable. Extra cold metal blanks cannot be painted or coated until they warm up to a certain temperature, such as 50 to 70 degrees F. Metal parts which have become hot from sitting in the sun may be too hot to paint or otherwise process, and must be allowed to cool down. As for security, a sharp knife can be used by vandals or others to gain access to the cargo.
Thus, there still exists a need for a truck trailer body or enclosure or covering suitable for use with a flat-bed trailer that protects against environmental damage, like a conventional rigid enclosed trailer, while providing essentially unfettered access. It would also be helpful to protect the cargo against temperature extremes during transit between nearby plants.
It accordingly is a main object of the present invention to provide an enclosure system for selectively covering cargo to be shipped by flat bed trailer over the highways, and protecting it from environmental damage during transport or when stored on the trailer, while still permitting the cargo on any part of the trailer to be rapidly and easily accessed.
A related object is to provide a trailer enclosure with several movable sections that can selectively provide unfettered access to the cargo space of a flat bed highway trailer, for inspection, loading and unloading.
Another object of the present invention is to provide a truck trailer body system with sliding nestable canopies for selectively protecting the cargo to be shipped by trailer over the highways from the environmental damage, while selectively providing largely open access to that cargo. Another object is to provide a truck trailer body system with sliding nestable rigid canopies that can be positioned at any number of locations along the bed of the trailer so as to expose any desired major section of the trailer bed or the cargo contained thereon.
Still another object of the present invention is to provide a truck trailer body system with sliding nestable interlocking canopies provided with restraining mechanisms that can be secured to prevent or minimize movement of the canopy sections during highway transport. Still other objects include providing a truck trailer body system with sliding nestable canopies that are insulated and weather-sealed to help keep out wind and environmental contaminants, and that optionally can contain means for controlling the temperature of the interior area of the truck trailer body.